Cd 34 glycoprotein as a differentiating marker between basal cell Carcinoma and Trichoepithelioma

Trichoepithelioma [TE] is a benign skin tumor with follicular differentiation, which is sometimes difficult to distinguish clinically and histologically from basal cell carcinoma [BCC]. One of the most helpful differences is the histologic appearance of the stroma. CD34 is an antigen known to stain the spindle shaped cells located around the middle portion of normal hair follicles. We selected twenty clinically confused cases. After routine histopathological staining by haematoxylin and eosin, all cases showed typical diagnosis in seventeen cases [9BCC and 8 TE] while the remaining three cases revealed overlapped features. Immunoperoxidase technique using anti-CD34 antibody carried out in all cases displayed two out of the three overlapped cases had a staining pattern similar to the typical BCC cases; the immediate tumor stroma together with the spindle cells intermixing the tumor nests were CD34 negative. Moreover, the remaining uncertainly diagnosed case had a pattern resembling the typical TE cases; the immediate tumor stroma as well as the spindle cells surrounding the tumor islands were focally CD34 positive. From our study, we concluded that the CD34 staining pattern can be considered as a helpful tool in differentiation between TE and BCC particularly when these lesians are in doubt about the clinical or routine histologic diagnosis